Selenium contamination, redistribution and remobilisation in sediments of Lake Macquarie, NSW Peters, G en_US Maher, WA en_US Jolley, D en_US Carroll, BI en_US Jenkinson, AV en_US McOrist, GD en_US 2021-11-25T13:33:02Z 2021-11-25T13:33:02Z 1999 en_US
dc.description.abstract This paper examines the history of selenium pollution in Lake Macquarie, NSW, Australia, and three factors that may affect the redistribution and remobilisation of particle bound selenium: changes in redox state, bioturbation, and bioaccumulation by macrobenthos and bacteria. Sediment cores were taken from Nords Wharf, a relatively unpolluted area, and from Mannering Bay near the Vales Point coal-fired power station. The age profile at the unpolluted site seems to indicate that mild selenium pollution has been occurring for over 100 years, however, some mixing of the sediments has occurred. At the polluted site, the age profile indicated that major contamination has occurred in the last 30 years, due to an ash dam associated with nearby electric power generation facilities. The contamination chronology suggests that remobilisation and reduction processes have affected the selenium profile. Changing the redox state of Lake Macquarie sediment results in a release of selenium under oxidising conditions and immobilisation under reducing conditions. The sediment-bound selenium was associated with the operationally defined `organic/sulfide' fraction under reducing conditions, and as the redox potential increases this moves into the `exchangeable' and `iron/manganese oxyhydroxide' phases to a limited extent. Bioturbation by the animals Marphysa sanguinea and Spisula trigonella caused increases in the redox potential and pore water selenium concentrations in surfcial sediments relative to unbioturbated controls. Both animals accumulated significantly more selenium when exposed to contaminated sediment than when exposed to uncontaminated control sediments. Selenium concentrations in molluscs from Mannering Bay were all significantly higher than those collected from Nords Wharf. Most of the selenium in the mollusc tissues was found to be associated with the protein fraction. Selenium isolated from hydrolysed muscle tissue was not present as selenate or selenite but as selenomethionine and an unidentified compound. Seven types of bacteria were isolated from Lake Macquarie sediment. All seven isolates were able to transform selenite quantitatively to elemental selenium as evidenced by a red precipitate and identified by X-ray diffraction. Six isolates grew on media containing selenate but no elemental selenium was formed. Mass balances showed that for three isolates total selenium was conserved, selenate decreased and selenium (0; II-) increased indicating the production of non-volatile organic selenium compounds. For two isolates both total selenium and selenate decreased with no increase in selenium (0; II-), therefore, loss of selenium occurred from the media. Selenium is immobile in anoxic reduced sediments but may become available to benthos and fish as a consequence of sediment oxidation associated with bioturbation leading to bioaccumulation and transformation by macrobenthos and bacteria. These mechanisms can be invoked as possible transport pathways to explain the presence of selenium above background concentrations in preindustrial sediments, but further work dating the sediments in which elevated concentrations of selenium are found is needed to confirm this hypothesis. en_US
dc.identifier.issn 0146-6380 en_US
dc.language English
dc.language.iso EN en_US
dc.rights CC BY-NC-ND 3.0 en_US
dc.rights.uri en_US
dc.source Legacy MARC en_US
dc.title Selenium contamination, redistribution and remobilisation in sediments of Lake Macquarie, NSW en_US
dc.type Journal Article en
dcterms.accessRights open access
dspace.entity.type Publication en_US
unsw.description.publisherStatement Journal homepage: en_US
unsw.identifier.doiPublisher en_US
unsw.relation.faculty Engineering
unsw.relation.ispartofissue 10 en_US
unsw.relation.ispartofjournal Organic Geochemistry en_US
unsw.relation.ispartofpagefrompageto 1287-1300 en_US
unsw.relation.ispartofvolume 30 en_US
unsw.relation.originalPublicationAffiliation Peters, G, Civil & Environmental Engineering, Faculty of Engineering, UNSW en_US
unsw.relation.originalPublicationAffiliation Maher, WA en_US
unsw.relation.originalPublicationAffiliation Jolley, D en_US
unsw.relation.originalPublicationAffiliation Carroll, BI en_US
unsw.relation.originalPublicationAffiliation Jenkinson, AV en_US
unsw.relation.originalPublicationAffiliation McOrist, GD en_US School of Civil and Environmental Engineering *
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